Yoga's postures, controlled breathing and meditation may work together to help ease brains plagued by anxiety or depression, a new study shows.

Brain scans of yoga practitioners showed a healthy boost in levels of the neurotransmitter gamma-aminobutyric (GABA) immediately after a one-hour yoga session. Low brain levels of GABA are associated with anxiety and depression, the researchers said.

"I am quite sure that this is the first study that's shown that there's a real, measurable change in a major neurotransmitter with a behavioral intervention such as yoga," said lead researcher Dr. Chris Streeter, assistant professor of psychiatry and neurology at the Boston University School of Medicine.

She believes yoga could prove a useful tool to help people battling depression and anxiety disorders. "We're not advocating that they chuck their medication, but I would advise that they could use it as an adjunct and see how they are doing," Streeter said.

Her team published its findings in the May issue of the Journal of Alternative and Complementary Medicine.